Vibrato Iconica sketch

Is Vibrato in Iconica sketch (or HSO for solo string instruments) adjustable? If so, what is the midi cc number for it?

No, in Iconica Sketch you can choose between using the sustain vibrato sound, or the sustain sound, but there’s no controllable parameter for the amount of vibrato.

That is good that I can choose vibrato. How can I choose vibrato vs non-vibrato for playback? Is there playing technique associated to distinguish this two?

By default, Dorico uses the sustain vibrato sound, because it was our consensus view that this sounds better overall than the plain sustain sound. You might prefer to use the plain sustain sound, in which case you should edit e.g. the Iconica Sketch Vlns, Vlas, Celli so that the Natural switch uses D#0 instead of F#0. You can then define e.g. a Vibrato switch and set it to use F#0. Now when you use the vibrato playing technique, it’ll switch to the sustain vibrato sound, and you can switch back to the regular sustain with nat..